Entries missing from iCloud calendar on PC browser

Many/most of my calendar entries have disappeared, but are still visible on my iPhone.

I can see the missing entries in the today’s calendar preview on icloud.com and if I go to the Daily calendar view. After I load daily view many of the entries show up again, but then disappear again when I click anything or when the webpage refreshes.

Problem doesn’t apply to older entries before Today, and is particularly bad on one calendar set which doesn’t even show up on day view. I have cleared my cache and check my icloud settings, but the webpage can clearly access them *sometimes*, but it is very intermittent.